With rapid development of the electronic product technologies, light emitting diodes (LEDs) have found increasingly wider application in, for example, the field of LED illumination, the field of liquid crystal display (LCD) and various industrial control display apparatuses.
In the field of liquid crystal display, a liquid crystal display device usually comprises a backlight module and a liquid crystal display panel superposed thereon. The liquid crystal panel cannot emit light by itself, so the backlight module is used as a light source in the liquid crystal display for driving the liquid crystal display panel display images. As a kind of typical point light source device, LEDs are often used in the backlight module as a key component. usually, a plurality of LEDs used as point light source are arrayed on the surface of a printed circuit board (PCB) to form an LED light bar, and the LEDs are driven by the PCB to emit light to form a bar-shaped line light source.
As is well known, the LED radiates heat during operation, in order to ensure that the LED operates within a preset temperature range, a heat dissipating component must be provided to form a light source assembly so that the heat generated by the LED during operation can be effectively and timely dissipated. Therefore, how to design a light source assembly with a desirable heat dissipating efficiency has become a great concern in the art.
A perspective view illustrating a structure of a prior art light source assembly is shown in FIG. 1. The light source assembly 1 comprises a plurality of LEDs 11, a PCB 13 and a heat sink 15. The array of the LEDs 11 is disposed on the surface of the PCB 13. The heat sink 15 is fixed to the PCB 13 by screws to form the light source assembly 1.
When the light source assembly 1 is working, the LEDs 11 generate massive heat which causes a sudden rise in the temperature of the whole PCB 13. Due to the phenomenon of thermal expansion and contraction effect, the whole PCB 13 tends to be deformed to cause a loose contact between the PCB 13 and the heat sink 15, which reduces the contact area and significantly degrades the heat dissipation efficiency. Furthermore, as assembled by use of screws, usually a tight fit cannot be achieved between the PCB 13 and the heat sink 15 due to inaccurate aligning operations performed by workers; which also reduces the contact area and significantly degrades the heat dissipation efficiency. More importantly, the use of the screwed structure leads to a large number of elements, a complex assembling process and an increased cost of the whole light source assembly 1.
Referring next to FIG. 2, there is shown a schematic side view of a structure of another light source assembly in the prior art. Likewise, the light source assembly 2 comprises a plurality of LEDs 21, a PCB 23 and a heat sink 25. The PCB 23 is fixedly adhered to the surface of the heat sink 25 directly by means of a thermally conductive adhesive layer 24.
In the light source assembly 2, although the use of the thermally conductive adhesive layer 24 simplifies the whole structure and the assembling process, there still exists the following problem: when the light source assembly 2 operates, the temperature of the thermally conductive colloid layer 24 increases with the temperature of the whole assembly, which causes aging and degradation in the adhesive performance of the chemical material of the thermally conductive colloid layer 24; this tends to cause loosing and falling off of the PCB 23 and the heat sink 25 from each other, thereby resulting in degraded heat dissipating performance and reliability of the product.
Accordingly, there exists a need in the art to provide an improved approach to fix a light source assembly.